Recommended Charge Profile for DIY LiFePO4 Batteries *Sticky Post*

[Will Prowse]

12V 4S LiFePO4 Battery w/ BMS:

• Absorption: 14.5V
• Float: 13.6V
• Inverter Cut-off: 10.7V-12V (depending on size of load and voltage drop etc)

24V 8S LiFePO4 Battery w/ BMS

• Absorption: 29V
• Float: 27.2V
• Inverter Cut-off: 21.4V-24V

48V 16S LiFePO4 Battery w/ BMS

• Absorption: 58V
• Float: 54.4V
• Inverter Cut-off: 42.8V-48V

Individual 3.2V LiFePO4 Raw Cell (for individual cell capacity testing)

• Absorption: 3.625V
• Float: 3.4V
• Low voltage disconnect for capacity testing: 2.5V

5,000+ Charge Cycle Absorption Recommendation
If you want your LiFePO4 cells to last a long time, you can set your absorption to Victron's custom LiFePO4 charge profile recommendation:

• 12V Battery: 14.1V
• 24V Battery: 28.2V
• 48V Battery: 56.4V

You can pull full capacity with the absorption figures above, but the charge rate will be reduced at high SOC.

Float should be 13.6V/27.2V/54.4V

Low voltage disconnect should be 12V/24V/48V

If you are not using a BMS (not recommended, for advanced users only)

1. Bottom balance the cells
2. Charge the cells at a .2C rate
3. The moment a cell hits 3.6V while charging, record the pack voltage
4. Manually set absorption for all chargers to the voltage in the previous step

If you are using used LiFePO4 cells w/ varying internal resistance readings, charge up to 3.525V per cell (12v/24v/48v absorption: 14V, 28V and 56V).

This will be a sticky post. If you disagree with a figure above, please message me with evidence to substantiate your claim. If something is missing, let me know :D